In order to obtain a good fuel economy with vehicle engines it has been proposed to arrange the operating process in such a manner that certain engine cylinders may be cut out when a low power output is required. This can be attained by in different ways and presupposes a fuel supply system, which permits the switching in and switching out the cylinders in question. On most occasions the pistons and the associated crank mechanism in these cylinders remained connected to the crank shaft, which causes wear and friction losses.
The aim of the present invention is to propose a vehicle engine, which is well suited for series production, and where it is possible to cut out a desired number of cylinders without any unnecessary frictional losses.
The invention is characterized in that the cylinders are arranged in two groups, each with an associated crank shaft part and operable by itself, that one crank shaft part by conventional clutch means is connectable to a power take-off shaft, and that the other crank shaft part is connectable to the power take-off shaft by transmission means running in parallel to the row of cylinders.
Each group of cylinders can be arranged in a separate engine block, the two blocks being interconnected to one unit. Alternatively all cylinders are located in a common engine block, the ends of the crank shafts being carried in a common bearing. The division between the crank shaft parts is preferably, but not necessarily, located adjacent to a cylinder from which the piston and the associated crank mechanism has been removed.
One group of cylinders may include a bigger number of cylinders than the other group. At least one of the cylinder groups may be provided with a balancing shaft (shafts).
The transmission means preferably includes parts adapted to permit a variation of the speed, for instance by the transmission means including a non-mechanical component.
Auxiliaries associated with the engine are preferably mounted at the end of the engine remote from the output shaft and the transmission means includes clutches permitting operation of the auxiliaries from either group of cylinders.
The smaller group of cylinders is preferably built-up of components substantially made of ceramic material, and this group is intended for operation with a high thermal load.